NOT APPLICABLE
NOT APPLICABLE
NOT APPLICABLE
This invention relates to the growing of grapes under rain protective plastic canopies. More particularly an improved tie down is disclosed for rain protective plastic canopies.
Grapes are typically grown in trellised dispositions. A typical trellis is either T-shaped or V-shaped and approximately 600 feet in length. While all grapes can be the subject matter of this invention, we are particularly concerned with problems of edible table grapes.
In the last six weeks before harvest, rain on table grapes is ruinous. It produces a mold on the grapes, which renders them unmarketable. The profits of a full growing season can be totally lost.
To avoid such a loss, it is known to cover the grapes with a plastic canopy. Typically, plastic material, either clear or opaque, is placed overlying the grapes. The canopy commences at the end of a trellis and continues uninterrupted to the other end of the trellis, typically covering both trellis ends. It is necessary to secure the canopy between the respective trellis ends. This securing between the trellis ends is done by discrete xe2x80x9ctie downs.xe2x80x9d It is the function of the tie downs to fasten the canopy overlying the grapes between the respective sides of the trellis on which the grape vines grow.
A plastic material used to form the canopies is typically a polyethylene film. The film is thin having a thickness of between 0.9 and 1.3 milts. The plastic must be thick enough and strong enough to maintain the waterproof covering over the grapes growing beneath the plastic. At the same time, if the plastic is too thick, it becomes prohibitively expensive and interferes with the maturation of the grape crop that it is intended to protect. Therefore, the thickness of a polyethylene film utilized to cover the grape vines is severely constrained.
The tie downs of the prior art have included at least two discrete forms. In a first form of tie down, a hole is punched in the plastic of the canopy material. Twine is tightened about the hole at one end an secured to either a trellis wire or alternately part of the vines at the other end. Tightening of the canopy occurs to hopefully produce a smooth and tight contour over the vine covered trellis.
This first form of tie down frequently fails by tearing through to the edge of the plastic film forming the canopy. A portion of the canopy material is ripped away. At the same time, the remaining portion of the canopy is free to move with the elements (which can include wind and rain) up and away from the trellised vines the canopy was placed to protect.
In a second form of tie down, a wad of material is gathered to the canopy material near the edge. The canopy material is gathered around the wad, which wad is about the size of the golf ball. Once the canopy material is gathered about the golf ball size wad, twine is tied both about the canopy material and the wad so as to trap wad through the canopy material and form a tie down point in the canopy material.
This technique has its own disadvantages. First, it takes too long; speed is of the essence when placing canopies to protect grape vines from oncoming inclement weather. Second, the wad of material most commonly available comprises leaves of the grape vines. This material is irregularly selected with some damage to the vines, and can tear the canopy at the point of attachment. Third, stretching of the canopy material occurs in the vicinity of the wad. The stretching produces irregularities in the canopy material from which tearing can propagate.
Since the canopy material overlies the grape crop for periods of from four to six weeks, adjustment of the canopy film is frequently required. This adjustment requires putting additional strain on the tie downs. Simply stated, where the tie downs are adjusted after relatively long periods of installation in the vineyard, failure of the originally installed tie downs occurs with relatively high frequency.
A protective polyethylene canopy, in the order of 100 to 110 inches in width and approximately 1.3 mils thick, is placed over trellised grapevines and fastened by the disclosed tie downs at the respective canopy sides. To form the tie downs, the side edges of the canopy are gathered and folded back upon themselves at intervals up to 2 inches. Thereafter, tape, in the form of adhesive labels, is placed over the folded edges so as to capture the folded and gathered side film edges. The label and folded film is transpierced, typically by a worker using grape clippers holding attached twine. Once transpierced and threaded with the twine, the twine is tied to the label and the canopy material, and then secured at its remote end to tightly secure the canopy overlying the trellis and vines growing on the trellis. The label is made from label face stock approximately 2xc2xd inches in width and 6 inches in length consisting of the opaque white spun bound polyolefin film having high tear strength with good moisture resistance. The label has a rubber based adhesive placed on the label backside, this rubber adhesive having the ability to adhere to the protective polyethylene canopy. The labels are in turn sequentially fastened to a continuous spiral wound release tape consisting of bleached, supercalendered paper stock supplied with and anti-block coating on the backside of the liner to control adhesive and label transfer when the labels are removed from the release tape. The resultant tie downs have approximately four times the strength of those previously utilized, are moisture resistant, and are capable of withstanding the wide thermal excursions the protective grape canopy experience in the last four to six weeks of grape maturation before harvest. As a result, the protective canopy can be fastened overlying the trellised grapevines at relatively high tension to enable a firm weather resistance requiring minimal maintenance.
An advantage of the disclosed tie down is that its installation is swift. In modern commercial grape growing environments, the onset of inclement weather requires swift placement of protective canopies over trellised grapevines. By way of example, utilizing the disclosed tie downs, 9000 rows of trellised vines, each trellis being over 600 feet in length, have been covered with a protective canopy in an eighteen hour period!
A further advantage of the disclosed tie down is that it is four times as strong as tie downs previously used. This being the case, no longer is the point of attachment of the twine to the protective canopy the weak point of the canopy securing system; with the disclosed tie down it is more common to have breakage in the twine.
A further advantage of the disclosed tie down is that superior tension can be applied to the protective canopy being utilized. This enables the protective canopy to be optimally shaped, securely held in place, and maintained with minimal maintenance adjustments until grape harvesting occurs.